Highly porous titanium and titanium alloys with an open cell structure are promising
implant materials due to their low elastic modulus, excellent bioactivity, biocompatibility and the
ability for bone regeneration. However, the mechanical strength of the porous titanium decreases
dramatically with increasing porosity, which is a prerequisite for the ingrowth of new bone tissues
and vascularization. In the present study, porous titanium with porosity gradients, i.e. solid core with
highly porous outer shell was successfully fabricated using a powder metallurgy approach.
Satisfactory mechanical properties derived from the solid core and osseointegration capacity derived
from the outer shell can be achieved simultaneously through the design of the porosity gradients of
the porous titanium. The outer shell of porous titanium exhibited a porous architecture very close to
that of natural bone, i.e. a porosity of 70% and pore size distribution in the range of 200 - 500 μm. The
peak stress and the elastic modulus of the porous titanium with a porosity gradient (an overall
porosity 63%) under compression were approximately 152 MPa and 4 GPa, respectively. These
properties are very close to those of natural bone. For comparison, porous titanium with a uniform
porosity of 63% was also prepared and characterised in the present study. The peak stress and the
elastic modulus were 109 MPa and 4 GPa, respectively. The topography of the porous titanium
affected the mechanical properties significantly.